1. Field of the Invention
The present invention relates to a front plate of a plasma display panel (PDP) and the method of fabricating the same. More particularly, the present invention relates to a method of fabricating a front plate of a plasma display panel that is capable of preventing oxidation of the electrodes in bonding area of the plasma display panel.
2. Description of the Related Art
Recently, a variety of flat panel displays, such as a liquid crystal display (LCD) and a plasma display. panel (PDP) have been intensively developed for replacing the cathode ray tubes (CRT) display. In PDP, an ultra violet light is emitted for exciting the RBG phosphors to produce visible lights. The advantages of the PDP include large display area, wide viewing angle, and intense brightness.
FIG. 1 shows an exploded view of a conventional plasma display panel (referred as PDP) comprising a front plate 10 and a back plate 12. The front plate 10 includes a glass substrate 14, a plurality of scanning electrodes 16, a transparent dielectric layer 18, and a magnesium oxide (MgO) layer 20. Each of the scanning electrodes 16 includes a sustaining electrode 22 and an auxiliary electrode 24. A visible light is emitted by plasma generated between two adjacent transparent electrodes 22 after a voltage is applied to these electrodes 22. In order to allow visible light to pass through the glass substrate 14, each of the sustaining electrodes 22 is a transparent electrode 22 consisted of indium tin oxide (ITO) or SnO2. However, the resistance of the sustaining electrode is too high to be suitable for electrical conduction. For this reason, an auxiliary electrode 24 consisting of metal is disposed on every sustaining electrode 22 to enhance conductivity.
The back plate 12 comprises another glass substrate 30, a plurality of data electrodes 32, a dielectric layer 33, a plurality of ribs 34, and a plurality of fluorescence layers 36. The data electrodes 32 of the back plate are perpendicularly to the scanning electrodes 16 of the front plate 10. The space formed by two adjacent ribs 34 and two adjacent scanning electrodes 16 is called a xe2x80x9cpixelxe2x80x9d. The data electrode 32 is used for controlling the generation of the plasma. The scanning electrodes 16 are used to maintain the plasma. In addition, the fluorescence layers 36 can produce primary visible lights after absorbing UV ray generated by the plasma. The primary visible lights includes red, green, and blue light. The ribs 34 prevent the UV ray from leaking to the neighboring pixel and thereby prevent the color mixing phenomenon.
Referring to FIGS. 2A through FIG. 2C, FIG. 2A shows a top view of the front plate of the PDP shown in FIG. 1, and FIGS. 2B and 2C show cross-sectional views of the front plate 10 along the axe2x80x94a and bxe2x80x94b lines shown in FIG. 2A, respectively. A pixel area and a bonding area are formed on the glass substrate 14, the axe2x80x94a line crosses the pixel area and the bxe2x80x94b line crosses the bonding area. The auxiliary electrode 24 is divided into a pixel auxiliary electrode and a bonding auxiliary electrode. The bonding auxiliary electrode is the portion of the auxiliary electrode 16 extending to the edge of the front plate 10 and used for connection to an external driving circuit (not shown). As shown in FIG. 2B, in the pixel area, the pixel auxiliary electrode is covered by the dielectric layer 18 and MgO layer 20. On the contract, in the bonding area as shown in FIG. 2C, the bonding auxiliary electrode is not covered by the dielectric layer 18 or MgO layer 20.
Conventionally, each of the scanning electrodes 16 is constituted of a sustaining electrode 22 and an auxiliary electrode 24 such that the auxiliary electrode 24 is stacked on top of the sustaining electrode 22. The auxiliary electrode 24 has a three-layered structure constituted of Crxe2x80x94Cuxe2x80x94Cr, wherein Cr and Cu denote chromium and copper, respectively. In particular, a heating process of about 500xc2x0 C. to 600xc2x0 C. is used to sinter the dielectric layer 18. However, the top Cr metal surface of the auxiliary electrode 24 tends to be oxidized easily during the heating process. It may cause a short circuit between the bonding auxiliary electrode and the external driving circuit, and the performance of the PDP will be reduced.
Therefore, the object of the present invention is to provide a front plate of a plasma display panel (PDP) capable of preventing the bonding electrode from being oxidized during the sequential heating process.
To achieve the above-mentioned object, the present invention provides a front plate of a PDP, comprising a glass substrate, an auxiliary electrode, and a protecting electrode. The auxiliary electrode is located on the glass substrate having a pixel area and a bonding area. The auxiliary electrode includes a pixel auxiliary electrode positioned at the pixel area and a bonding auxiliary electrode positioned at the bonding area. The protecting electrode is disposed above the bonding auxiliary electrode so that the bonding auxiliary electrode is covered by the protecting electrode and is not oxidized during the sequential processes.
According to the first embodiment of the present invention, the glass substrate includes a trench and the auxiliary electrode is embedded in the trench of the glass substrate. The auxiliary electrode includes a main conducting layer, a first medium layer positioned between the main conducting layer and the glass substrate, and a second medium layer positioned between the main conducting layer and the protecting electrode. The first medium layer is used to eliminate the stress between the main conducting layer and the glass substrate, and the second medium layer is used to eliminate the stress between the main conducting layer and the protecting electrode.
According to the second embodiment of the present invention, the glass substrate includes a trench, and the auxiliary electrode is embedded in the trench of the glass substrate. The auxiliary electrode includes a main conducting layer positioned under the protecting electrode and a first medium layer positioned between the main conducting layer and the glass substrate. The first medium layer is used to eliminate the stress between the main conducting layer and the glass substrate.
According to the third embodiment of the present invention, the front plate further incldues a buffer layer located on the glass substrate. The buffer layer has a trench and the auxiliary electrode is embedded in the trench of the buffer layer. The auxiliary electrode includes a main conducting layer, a first medium layer positioned between the main conducting layer and the buffer layer, and a second medium layer positioned between the main conducting layer and the protecting electrode. The first medium layer is used to eliminate the stress between the main conducting layer and the buffer layer, and the second medium layer is used to eliminate the stress between the main conducting layer and the protecting electrode.
According to the fourth embodiment of the present invention, the front plate further includes a buffer layer located on the glass substrate, the buffer layer has a trench, and the auxiliary electrode is embedded in the trench of the buffer layer. The auxiliary electrode includes a main conducting layer positioned under the protecting electrode and a first medium layer positioned between the main conducting layer and the buffer layer. The first medium layer is used to eliminate the stress between the main conducting layer and the buffer layer.
According to the fifth embodiment of the present invention, the front plate further includes a sustaining electrode located between the glass substrate and the auxiliary electrode. The auxiliary electrode includes a main conducting layer, a first medium layer positioned between the main conducting layer and the sustaining electrode, and a second medium layer positioned between the main conducting layer and the protecting electrode.
According to the sixth embodiment of the present invention, the front plate further includes a sustaining electrode located between the glass substrate and the auxiliary electrode. The auxiliary electrode includes a main conducting layer positioned under the protecting electrode and a first medium layer positioned between the main conducting layer and the sustaining electrode.
According to the embodiments of the present invention, the main conducting layer is made of copper (Cu), the first and the second medium layers are made of chromium (Cr) Furthermore, the protecting electrode is made of a layer of metal-oxide, which is selected from the group of ITO (Indium Tin Oxide), ZnO (Zinc Oxide), and SnO2 (Stannum dioxide).
A method of fabricating the above-described front plate a PDP according to the present invention includes the steps of: (a) providing a glass substrate having a pixel area and a bonding area; (b) forming a trench in the glass substrate; (c) forming an auxiliary electrode in the trench, wherein the auxiliary electrode comprises a pixel auxiliary electrode disposed in the pixel area and a bonding auxiliary electrode disposed in the bonding area; and (d) forming a protecting electrode-over the bonding auxiliary electrode to prevent the bonding auxiliary electrode from oxidation during the sequential process.
A further method of fabricating the above-described front plate a PDP according to the present invention comprises the steps of: (a) providing a glass substrate having a pixel area and a bonding area; (b) forming a dielectric layer on the glass substrate; (c) forming a trench on the dielectric layer; (d) forming an auxiliary electrode in the trench, wherein the auxiliary electrode comprises a pixel auxiliary electrode disposed in the pixel area and a bonding auxiliary electrode disposed in the bonding area; and (e) forming a protecting electrode over the bonding auxiliary electrode to prevent the bonding auxiliary electrode from oxidation during the sequential process.
A further method of fabricating the above-described front plate a PDP according to the present invention comprises the steps of: (a) providing a glass substrate having a pixel area and a bonding area; (b) forming a transparent electrode on the glass substrate; (c) forming an auxiliary electrode above the transparent electrode, the auxiliary electrode comprising a pixel auxiliary electrode disposed in the pixel area and a bonding auxiliary electrode disposed in the bonding pad area; and (d) forming a protecting electrode on the auxiliary electrode to prevent the bonding auxiliary electrode from oxidation.